Elevators are conventionally provided with a safety brake. A safety brake is designed to bring an elevator cab or gondola to a halt in case of an emergency. The safety brake is a redundant device. In most elevators, the motor that drives the elevator has its own braking system that is used in normal operation, with the safety brake only engaging during a fault condition.
Previous systems for providing a safety brake include mainly passive means for detecting only the most serious faults, such as a break in the hoist cable. Other conditions, such as a power failure or an overspeed condition not resulting from a hoist cable break, are not necessarily addressed within the safety brake mechanism. Further, prior safety brake designs can be primitive, serving the basic need of life safety but having other negative effects. For example, one such design for an incline elevator involves a hook that swings back and catches a portion of the elevator framework, resulting in a sudden arrest of downward travel of the elevator cab that is uncomfortable for passengers, and additionally resulting in possible damage to the elevator framework itself.
For maximum safety, it is desirable to provide a safety break design which engages upon detection of any one of a number of different faults. Optimally, the system would detect both mechanical and electrical faults. For passenger comfort and minimization of mechanical damage to the elevator following a deployment of the safety brake, a smoother deceleration to a stop is also desirable. Further, new building and construction codes coming into vogue require levels of redundancy for elevator safety brakes not previously implemented.
Accordingly, this application discloses a system for a safety brake for incline elevators.